Phosphorus (P) is one of the most essential macronutrients required for the growth of plants and is added to soil in the form of phosphatic fertilizers. However, because of mineral re-precipitation, large amount of applied phosphate fertilizer may become unavailable to the plant. The ability of soil microorganisms to transform insoluble forms of phosphorus to an accessible form is an important path in plant growth-promoting for increasing plant yields. In this study, Aspergillus Niger, a fungal strain isolated from agricultural soil samples, was tested for its ability to solubilize different phosphated matrixes (TCP, DCP, phosphates rock). The isolated fungus exhibits high capacities to solubilize all tested phosphates. The solubilization of insoluble phosphates was associated with a drop in the pH of the culture medium. The fungal biomass was entrapped in alginate and polyacrylamide gels and was used for solubilizing mineral phosphates in fluidized bed bioreactor. The highest specific solubilization rates were obtained when A. Niger was entrapped in alginate beads. The use of the bioreactor in consecutive cycles of solubilization showed the interest of the biomass immobilization in the stability of the bioreactor. Immobilized cells in alginate continuously solubilize phosphate even after 5 cycles of solubilization without loss of activity. The phosphorus biosolubilization performances of isolated strains may open new possibilities for their biotechnology application and allow the use of this fungus in the soil fertilization.